Maximum Discharge Flow Research Articles

Computational approaches for annual maximum river flow series

Abstract Studies of annual peak discharge and its temporal variations are widely used in the planning and decision making process of water resources management. Very recently, soft computing techniques are gaining ground for time series analysis of hydrological events such as rainfall and runoff. In this study Artificial Neural Network (ANN) has been used in combination with wavelet to model the annual maximum flow discharge of rivers. The results of ANN-Wavelet (WANN) model indicate overall low coherence (R2 = 0.39) better than ANN (R2 = 0.31) in isolation. In the present analysis, the authors also conceded a probabilistic distributional analysis of river flow time series which has greater potential to better reflect peak flow dynamics. The results highlight that the overall performance of probability distribution models is superior to WANN model. Instead of that WANN is better than probabilistic models to find the global maxima of the series.

The 27 May 1937 catastrophic flow failure of gold tailings at Tlalpujahua, Michoacán, Mexico

Abstract. On 27 May 1937, after one week of sustained heavy rainfall, a voluminous flood caused the death of at least 300 people and the destruction of the historic El Carmen church and several neighborhoods in the mining region of Tlalpujahua, Michoacán, central Mexico. This destructive flood was triggered by the breaching of the impoundment of the Los Cedros tailings and the sudden release of circa 16 Mt of water-saturated waste materials. The muddy silty flood, moving at estimated speeds of 20–25 m s−1, was channelized along the Dos Estrellas and Tlalpujahua drainages and devastated everything along its flow path. After advancing 2.5 km downstream, the flood slammed into El Carmen church and surrounding houses at estimated speeds of ~ 7 m s−1, destroying many construction walls and covering the church floor with ~ 2 m of mud and debris. Revision of eyewitness accounts and newspaper articles, together with analysis of archived photographic materials, indicated that the flood consisted of three muddy pulses. Stratigraphic relations and granulometric data for selected proximal and distal samples show that the flood behaved as a hyperconcentrated flow along most of its trajectory. A total volume of the Lamas flood deposit was estimated as 1.5 × 106 m3. The physically based bidimensional (2-D) hydraulic model FLO-2D was implemented to reproduce the breached flow (0.5 sediment concentration) with a maximum flow discharge of 8000 m3 s−1 for a total outflow volume (sediment + water) of 2.5 × 106 m3, similar to the calculations obtained using field measurements. Even though premonitory signs of possible impoundment failure were reported days before the flood, and people living downstream were alerted, authorities ordered no evacuations or other mitigative actions. The catastrophic flood at Tlalpujahua provides a well-documented, though tragic, example of impoundment breaching of a tailings dam caused by the combined effects of intense rainfall, dam weakness, and inadequate emergency-management protocols – unfortunately an all-too-common case scenario for most of the world's mining regions.

A study on coordination between urban development and station capacity

In Tokyo, recently, rapid urban developments around railway stations in the city centre have been causing serious overcrowding at the stations. However, rapid urban development around the station brings immediate load on the station, there is almost no research to solve this problem. Therefore, this study tries to study towards solutions for preventing the overcrowding at stations caused by urban development in the city centre. Concretely, (1) it identifies causes of the overcrowding at city central stations in Tokyo. (2) Next, conducts a fact-finding survey of the overcrowding at stations, we suggested the ‘maximum discharge flow for a station facility’ as how much the station facility can accept in terms of the increase of passengers. (3) Lastly, based on the results of (1) and (2), we suggested what should be improved institutionally to prevent serious overcrowding at stations.

Breaking mode of cohesive homogeneous earth-rock-fill dam by overtopping flow

Breaking tests on homogeneous earth-rock-fill dams destroyed by overtopping flow are presented. Two types of shear erosion are found: wetting shear erosion and quick shear erosion; the water level-discharge process is divided into “sharp rise and drop of flow” and “slow change of flow” types. Furthermore, overtopping break modes are divided into head-cut erosion and scour breaching mode (Mode 1), shear erosion and collapse breaching mode (Mode 2), and wetting shear erosion mode (Mode 3) based on the main failure types and their coupled mode during dam break. In Mode 1, the downstream slope encounters head-cut erosion at the onset of the breach and expands and undercuts gradually at the development stage; in Mode 2, the dam slope encounters rapid shear erosion and the downstream edge of the crest erodes quickly towards the upstream face at the onset of breach: the breach expands suddenly due to instability and collapse at both sides of the breach in its development stage; in Mode 3, the strength of the dam’s materials continuously decreases by wetting and erosion happens is localised at positions where wetting caused the most strength loss, no obvious breach was developed. Dam breaking time, dam-break flow process, and the maximum discharge flow varied for each breaking mode. Overtopping flow size, materials, height, and initial breach size of dam are important factors influencing breaking mode, by virtue of their changing the relative strength of the relationship between the critical shear stress of dam materials at the edge of the dam crest and the lower parts of its slope, and the given flow’s destruction capacity. Overtopping will cause different manifestations of damage to be exhibited, so modal classification is favourable for safety assessment and preparation of relevant protective measures for protection of earth-rock-fill dam against overtopping.

Capacity Estimation for Weaving Segments Using a Lane-Changing Model

During peak periods, freeway bottlenecks can be activated by intensive lane changing at weaving segments, where merging and diverging areas are in close proximity. This weaving phenomenon has a major impact on capacity. Much research has been devoted to investigating capacity estimation models for weaving segments. However, because of the model parameters, estimation models are difficult to adopt directly in active traffic management strategies to estimate real-time maximum discharge flow. To this end, this study defined a linear optimization problem to solve weaving capacity and then established a lane-changing model to constrain the weaving flows. The proposed method was evaluated and analyzed for sensitivity with field data from two weaving segments on Whitemud Drive, Edmonton, Alberta, Canada. The capacity estimates from the proposed model were consistent with that from the Highway Capacity Manual 2010 model and with field observations. Moreover, it was also observed that the weaving capacity was sensitive to weaving maneuvers. Finally, the proposed method was applied to estimate the real-time maximum discharge flow rate; the estimates matched field measurements. These findings could lead to implementations in designing optimal traffic control strategies.

An investigation of wash-off controlling parameters at urban and commercial monitoring sites

The relationship between the parameters of the wash-off function and the controlling hydrologic variables are investigated in this paper, assuming that the pollutant generation process basically depends on the watershed rainfall-runoff response characteristics. Data collected during an intense monitoring program carried out by the Department of Environmental Engineering of the University of Genova (Italy) within a residential area, an auto dismantler facility, a tourism terminal and a urban waste truck depot are used to this aim. The observed runoff events are classified into different TSS mass delivery processes and the occurrence of the first flush phenomenon is also investigated. The correlation between the mathematical parameters describing the exponential process and the hydrological parameters of the corresponding rainfall-runoff event is analysed: runoff parameters and in particular the maximum flow discharge over the time of concentration of the drainage network are proposed as the controlling factor for the total mass of pollutant that is made available for wash-off during each runoff event.

Hydrologic influence on stormwater pollution at two urban monitoring sites

The pollutant transport process operated by stormwater runoff on urban paved surfaces and the relationship between the parameters of the wash-off function and the controlling hydrologic variables are investigated in the present work. Data collected during two monitoring campaigns carried out at the plot scale within a residential area and an auto dismantler site are used to this aim. The observed runoff events are classified into different mass delivery processes and the occurrence of the first flush phenomenon is also investigated. The maximum flow discharge obtained as the average value over the time of concentration of the drainage network is proposed as the controlling factor for the total mass of pollutant that is made available for wash-off during each runoff event.

Discharge demand analysis on a drainage stack for residential buildings

PurposeTo determine the probable drainage load for sizing a stack serving a number of domestic washrooms in high‐rise buildings, with various occupant loads served by an appliance and simultaneous use of appliances in a domestic washroom taken into account.Design/methodology/approachWith the reported probable demand patterns of domestic appliances from laboratory testing results, on‐site measurements and survey studies, the probable maximum discharge flow rates from a number of domestic washrooms in a stack are estimated with Monte‐Carlo simulations.FindingsThe results demonstrated that the occupant loads and the usage patterns of an appliance had significant effects on the sizing of a drainage stack. It was reported that a reduction of 16 per cent in the design discharge flow rate for a washroom, at an occupant load of 4.2 persons per apartment, could be achieved with no more than one appliance discharging at a time. Influence of the occupant load served by an appliance on the probable maximum drainage demand at the stack was addressed. The results also showed a reduction of the predicted discharge flow rate at the stack serving a number of typical domestic washrooms from −26 to +21 per cent as compared with those predicted by the nominal occupant load in current practice.Research limitations/implicationsThe model parameters were determined from surveys for some high‐rise residential buildings in Hong Kong and from some laboratory testing results for typical domestic sanitary appliances. The model therefore may require adaptation for use in other countries.Practical implicationsA useful source of information in determining the stack size serving a number of domestic washrooms for those involved in building design and management related to drainage systems of residential buildings.Originality/valueThis paper proposes mathematical expressions in sizing a drainage stack serving a number of domestic washrooms in high‐rise buildings, where drainage demands are dependent on the building occupant loads at certain discharge patterns of appliances in a domestic washroom.